Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 683	$ 660	$ 1,170	$ 1,022
Net actuarial gains (losses) of defined benefit plans:
Adjustment	(5)	48	(7)	80
Recognized within Net income	11	16	21	33
Prior service cost of defined benefit plans:
Adjustment	0	(1)	0	(2)
Recognized within Net income	1	(2)	1	(2)
Derivative instruments:
Change in fair value	0	(1)	0	(1)
Recognized within Net income	1	0	1	1
Other comprehensive income (loss)	8	60	16	109
Total comprehensive income	$ 691	$ 720	$ 1,186	$ 1,131